The alphanumeric telephone keypad matrix is known in the art. The universally recognized standard for the push button telephone keypad is a 4.times.3 matrix having four rows and three columns of buttons, or keys. Each key is preassigned with a single digit or special symbol as a primary assignment, and with three alphabetic characters as a secondary functional assignment.
Automatic response function telephone systems, computerized systems, are designed to route incoming calls from pay or non-pay calling stations to a computer. An incoming call is received and processed by the computer which typically prompts the caller to select the desired service by pressing numeric keys on the telephone keypad. The identity of each numerical key is determined from an analog, dual tone multifrequency signal (DTMF) which is generated upon depressing the numerical key. The DTMF is a combination of two analog voice frequency tones, and it addresses stored digital code. Timing is typically not critical in the entry of DTMF signals for the identification of the numerals of standard, numerical keys. The computer converts the analog DTMF tones into digit signals for processing. The computer may also convert digit signals into analog voice signals for providing acknowledgement/prompt messages to the caller.
For example, by pressing the numeral 1 on the keypad in response to a computerized voice prompt, the caller may be connected to the technical support department, or by pressing the 0 on the keypad, the caller may be connected to an operator for further assistance. Computerized telephone systems may also eliminate voice communication and require the caller to communicate exclusively through the telephone keypad. In one such application wherein a caller desires that information be delivered by facsimile, the caller may press the number key corresponding to the number of the desired document and, upon entry of the start button or the receiving facsimile number, the document will be delivered.
Entry of the letters of the alphabet is desirable for many reasons and purposes including automatic response function telephone systems. For example, the caller's name and address may be needed to complete the telephone transaction.
While the universally recognized 4.times.3 keypad of the prior art standardizes the physical arrangement of the numeric characters, the physical arrangement of alphabetic characters may vary. One typical push button telephone matrix of the prior art includes twenty four letters of the alphabet, excluding the "Q" and the "Z", arranged on eight of the twelve keys as follows:
______________________________________ KEY 1 No letters KEY 2 ABC KEY 3 DEF KEY 4 GHI KEY 5 JKL KEY 6 MNO KEY 7 PRS KEY 8 TUV KEY 9 WXY KEY 0 No letters KEY * No letters KEY # No letters ______________________________________
There are several methods of entering alphabetical characters using the conventional telephone keypad design outlined above. None of the methods provide for the DTMF signal entry of alphabetical characters, and timing of entry is critical in the first prior art method.
The first method requires the caller to locate the desired letter on the telephone keypad and to press the corresponding key either once, twice, or three times, depending upon the location of the desired letter on the key. For example, to enter the name "JONES", the following steps are required:
______________________________________ KEY 5 Press once (Pause) KEY 6 Press three times (Pause) KEY 6 Press twice (Pause) KEY 3 Press twice (Pause) KEY 7 Press three times (Pause) ______________________________________
The first method does not permit the caller to enter digits and letters within the same word. The method is time critical in that pressing the Number 1 key three times in a row could provide for the input of the letters C, or AB, or BA, or AAA depending upon the timing between keystrokes. Because the number of keystrokes used to enter letters is not constant, the caller is required to provide considerable concentration to correctly complete the desired entry. In addition, it is difficult to store frequently used words in a system having an autodialing capability because of the necessity for introducing pauses between characters.
A second method for entering letters of the alphabet requires the caller to locate and press the key bearing the desired letter and then to press the key bearing the numeral corresponding to the position of the desired letter on the key. For example, to enter the letter "H", the caller must first press the number four key which bears the letter "H", and must then press the number two key because the "H" is the "second" letter on the number four key. The following steps are required to enter the name "JONES" using the second method:
______________________________________ KEY 5 Press once KEY 1 Press once (Pause) KEY 6 Press once KEY 3 Press once (Pause) KEY 6 Press once KEY 2 Press once (Pause) KEY 3 Press once KEY 2 Press once (Pause) KEY 7 Press once KEY 3 Press once ______________________________________
Although the second method standardizes the number of keystrokes for each letter, it requires considerable concentration by the caller to properly complete the required keystrokes.
As can be seen from the above summary of the prior art, an unsolved need exists for a simple method and apparatus for inputting alphabetical and numeric characters into a telephone system.